Filtration apparatus

ABSTRACT

The invention is concerned with the disposal of effluent material, e.g. on agricultural land which is difficult to handle. The feature of the invention is an apparatus which can handle solid liquid slurries by squeezing the slurry through a nip between a rotatable apertured shell and squeeze rolls having deformable outer surfaces which are positioned above and beneath the apertured shell and in contact therewith. The shell is supported for rotation and is rotated by the squeeze rolls which are driven in sufficiently firm contact with the shell to achieve this effect and to assist in the passage of effluent material through the nip. A further feature of using deformable squeeze rolls is that the lower roll extends into the apertures in the shells so as to keep them substantially clear of solid material. The effluent is normally fed to the top surface of the shell immediately before the nip and filter liquor passing through the shell is collected by appropriate means. Liquid with a very small amount of solid material is handled by using two pairs of squeeze rolls on one shell and feeding to the shell before the nip of the first rolls a fibrous material which forms a mat on the shell surface between the two nips. The mainly liquid effluent is then fed onto this mat between the two sets of squeeze rolls.

United States Patent Laurie et al.

[54] FILTRATION APPARATUS [72] Inventors: James Harold Laurie, Old Hall Farm, Carleton Rode, Norwich, Norfolk; Raymond Alfred Cole, Feildings Heywood-Diss, Norfolk, both of England [22] Filed: Dec. 21, 1970 [21] Appl. No.: 102,402

[52] US. Cl. ..100/121, 100/75 [51] Int. Cl. ..B30b 9/20 [58] Field of Search ..100/116, 117, l2l,73,74,

Primary Examiner-Peter Feldman Attorney-W. R. Liberman 1451 Dec. 12, 1972 [57] ABSTRACT The invention is concerned with the disposal of effluent material, e.g. on agricultural land which is difficult to handle. The feature of the invention is an apparatus which can handle solid liquid slurries by squeezing the slurry through a nip between a rotatable apertured shell and squeeze rolls having deformable outer surfaces which are positioned above and beneath the apertured shell and in contact therewith. The shell is supported for rotation and is rotated by the squeeze rolls which are driven in sufficiently firm contact with the shell to achieve this effect and to assist in the passage of effluent material through the nip. A further feature of using deformable squeeze rolls is that the lower roll extends into the apertures in the shells so as to keep them substantially clear of solid material. The effluent is normally fed to the top surface of the shell immediately before the nip and filter liquor passing through the shell is collected by appropriate means. Liquid with a very small amount of solid material is handled by using two pairs of squeeze rolls on one shell and feeding to the shell before the nip of the first rolls a fibrous material which forms a mat on the shell surface between the two nips. The mainly liquid effluent is then fed onto this mat between the two sets of squeeze rolls.

12 Claims, 17 Drawing Figures PATENTEU nu: 12 m2 SHEET 1 [1F 5 'IIIII'IIIIIIIIII.

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PATENTEDBEC 12 I972 3' 705. 547

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FILTRATION APPARATUS This invention relates to the dewatering of liquid and liquid solid effluent material.

A major problem in agriculture and industry is the existence of large volumes of effluent material which is difficult to handle and to dispose of. Storage of effluent on waste land is only a limited solution and disposal is governed by pollution control which is increasingly strict.

One of the difficulties encountered in dealing with liquid solid effiuent such as cow, pig, and poultry slurry, generally known as farm slurry, is the filtration problem encountered. The centrifuges suggested for the filtration of farm slurry have only been partially successful.

' We have sought to devise an apparatus of simple and robust nature which would deal effectively with various kinds of mainly liquid or liquid solid agricultural and industrial effluent, in some cases with adaptations within the scope of this invention to handle materials which are particularly difficult to filter.

According to our invention we'provide a filtration apparatus which comprises a filter plate constituted by a cylindrical shell rotatable around its longitudinal axis and perforated over its entire surface to allow the passage of filtered liquor therethrough; at least on pair of squeeze rolls mounted opposition one another above and beneath the surface of the shell and in contact therewith, the shell being drivable by rotation of the squeeze rolls and the outer surfaces of the rolls being deformable by their contact with the shell; means for driving both rolls; feed means arranged to supply effluent to the top surface of the shell immediately before the nip between the shell and squeeze rolls, in the direction of rotation of the shell by the rolls, whereby the effluent is carried by the shell into the nip and forced between the rolls under compression, filter liquor passing through the perforations in the shell and solid material being carried past the nip; means for collecting filter liquor passing through the shell; and a scraper member located beyond the nip in the direction of movement of the shell to detach solid material from the top surface of the shell.

In many cases, it is desirable to effect only partial dewatering of a liquid solid effluent in a first stage filter as just defined and to provide a substantially identical second filter which receives partially dewatered solid material from the first stage and achieves the remaining dewatering more effectively than would be the case in a single stage filter.

The apparatus of the invention may be used effectively to filter sludge with a low solid content. In this case, a further pair of opposed squeeze rolls is arranged in contact with the top and bottom surface of the shell adjacent to the pair described above and also assisting in driving the shell. Solid material to act as a filter aid such as sawdust or waste fiber e.g., straw, is then fed to the first pair of squeeze rolls precisely as described above in the case of the single pair, and the sludge is then fed to the surface of the shell between the two pairs of squeeze rolls.

In the accompanying diagrammatic drawings:

FIG. 1 is an elevation of one form of filtration apparatus according to the invention;

FIGS. 18, 1C, 1D and 2 show details of FIG. 1; (FIG. 1B being a section along the line 18-18 and FIGS. EC

and 1D being a sectional elevation and a cross-section respectively of a detail of FIG. 1;

FIG. 3 is a modification of FIG. 1;

FIG. 3A is a detail of FIG. 3;

FIGS. 4 to 7 are diagrams illustrating details of the apparatus;

FIG. 8 is a further modification;

FIGS. 9 and 11 are side views and FIG. 10 a front view corresponding to FIG. 3;

FIG. 9A shows a detail of FIGS. 9-11; and

FIG. 12 is a side view of a further modification.

The filtration device shown in FIG. 1 comprises a cylindrical metal shell I mounted within a tubular metal frame 6 (FIGS. 9 to 11 and 12) so as to rotate substantially freely within the frame. The shell has upturned flanges 10 welded on at the rims (FIG. 1B). The shell is supported between a pair of driven squeeze rolls 2 mounted at the top of the frame one above the other in opposition and both compressed against the surface of the shell. FIGS. 1C and 1D show one form of roll 2. The core 20 is of mild steel and the outer sleeve 30 is synthetic rubber of -85 B.S. hardness. The roll 2 may be made in various ways, e.g., laminated or with an extruded sleeve fixed by adhesive to the core. Guide rollers 3 are supported by the tubular frame against the inside surface of the shell to provide additional support and guidance when the shell is rotated. The upper roll 2 is spring loaded asshown at 51 in FIG. 12.

An agitated force-feeding device is shown in FIG. 1. The pivoted arm 41 is reciprocated by the crank 42 with spring biasing 43. In the dotted position, stones for example are forced through the nip.

The cylinder 1 is perforated over its entire surface so as to act as a filter plate in the apparatus. As shown in FIG. 2, the rubber sleeve 30 is deformed so as to penetrate at least partly into the perforations 4 as the shell is driven through the nip 5. in this way, the perforations. 4 are kept clear of clogging material. The lower roll 2 is driven by a low geared motor 8 through a chain and sprocket drive 7. The upper roll 2 is driven by the lower roll through gearing 23 (FIG. 9A).

FIG. 3 shows a modification more fully illustrated in FIGS. 9 to 11 and 12.

A further shell 1A with similar squeeze rolls 2A constitutes a second stage of the filtration apparatus, and its squeeze rolls are driven by the same motor 8 (not shown in FIG. 3) in the same way. Each of the two stages has a liquid trough 9 positioned to collect liquid filtering through the perforations immediately beneath and on each side of the nip between the squeeze rolls and the shell. A two-stage hopper 11 is provided for feeding effluent to be filtered to the surface of the cylinder immediately before the nip with the squeeze rolls. The effluent enters the first stage through an inlet port 12 and passes underneath a battle 13 constituting a trap for stone or other solid material above a required mesh size which is to be held back (FIG. 3A). The upper surface of the shell constitutes a base for the hopper and rubber seals 14 are provided at the foot of the rear wall of the hopper and at the sides (not shown) to retain effluent feed. The effluent in the second stage of the feed hopper is maintained at a constant level by an overflow tube 15, so as to give an even distribution over the perforated cylinder base and to provide a slight head pressure which assists in the entry of material between the shell and the upper squeeze roll.

The partially dewatered material leaving the nip in the first stage filter is detached from the upper surface of the shell by a scraper chute 16,18 positioned to contact the shell surface at an acute angle beyond the nip with the squeeze rolls. The detached material is fed along a chute 18 (FIG. 9) to the nip 5A of the second stage filter. The collected liquid from the troughs 9 is fed to a common outlet point (not shown) by a pump 17.

Each pair of opposing squeeze rolls are geared to one another at 23 and 23A, respectively (FIG. 9A) and the lower rolls are driven by the motor 8 (FIG. 9) through the chain and sprocket drives 7 and 7A, respectively.

A brush (24) is positioned on the outside of each shell so as to assist in the cleaning of the perforations 4 which are additionally kept clean by the action of the compressible surfaces of the lower squeeze rolls 2 and 2A entering the perforations at least partly as shown at 19 (FIG. 2), and also by the action of the scraper chute 16,18 and scraper 21 (FIG. positioned to contact the shells l and 1A, respectively, after the nips 5 and 5A. The nearly dry material leaving the nip of the second stage filter is collected for storage in a bin 22.

When farm slurry, namely cow, pig or poultry slurry is to be fed to the filtration apparatus, this is normally collected first in holding channels or pits. Water may be added to the slurry and the slurry may be held for a required period to allow for chemical change or for liquid fiber separation conditions. It is then pumped to the hopper 1 1 on the first stage filter (FIG. 3).

Although a two-stage filter has been described above, it will be appreciated that a simplified apparatus may be used with one shell and a co-operating pair of squeeze rolls only. The advantages of having two stages is that it is more economical to remove a large proportion of the water content in the first stage and to effect the final dewatering in a second stage.

A particularly advantageous embodiment comprises a single shell with two pairs of squeeze rolls (see FIG. 5 below).

It is a feature of the apparatus just described that both top and bottom squeeze rolls 2 are driven one directly and the other through gearing and also that the rolls are made of deformable material, preferably rubber. The bottom roll assists the upper roll in driving the shell, but also acts to keep the perforations clean. The top roll is sufficiently deformable to allow stones below a certain mesh size which have been allowed through by the stone trap to pass through the nip.

The front wall of the hopper extends to a location about half-way down the top rolls, so that the top roll effectively constitutes a portion of the front wall of the hopper.

The scraper 21 employed is normally a floating scraper blade which is spring loaded, e.g., at 25 and is positioned so as to contact the shell surface slightly above the center position.

A modification of the construction described above consists in an adaptation to deal with sludge containing only fine solid material and representing a major filtration problem.

In this case, one or more pairs of opposed squeeze rolls similar to the rolls described above are mounted on one shell in precisely the same manner, and adjacent to one another, to provide one or more receiving surfaces on the shells between the nips of the adjacent pairs of rolls (see FIGS. 4 8). The modified apparatus may have two feeds 31,32 (FIG. 5), one of which (31) supplies a solid, fibrous material such as sawdust or straw to a location of the shell surface immediately before the first of two pairs of rolls 2 and the other of which (32) feeds sludge to the region 26 between the two pairs.

The first pair of rolls 2 compacts the solid material passing through the nip with the shell and causes it to form a receiving mat on the surface of the shell between the two pairs of rolls. The mainly liquid slurry supplied at 32 comes first into contact with this mat which acts as a filter aid and is therefore sufficiently held back for filtration to be effective. The rest of the operation of the apparatus is similar to that described above, but in this case a single filtration stage is sufficient since the major problem is to deal with a mainly liquid material as opposed to the above cases where the solid material was a major component of the original effluent. However, in this case also, it is possible to use two stages if it is desired to recover the sawdust or straw used as the filter aid in a mainly dry condition.

FIG. 8 shows an arrangement of two pairs of squeeze rolls 2 acting on one shell 1. The liquid is fed into a common trough 9. The arrangement works as a twostage filter. The additional hopper 11A may be used for sludge filtration. If ordinary farm slurry is fed at 11, enough fiber is deposited at 33 for the sludge fed at 11A to be effectively filtered through the second nip.

Various modifications and refinements may be made in the aboveapparatus.

Thus, we need only make the lower roll 2 deformable. Although operation may be less effective in that case because of reduced friction on the shell, which means less drive, there is less wear on the upper roll which may e.g., of mild steel.

Alternatively, instead of solid deformable rolls in each case the upper rubber roll for example may be a pneumatic roll.

The kind of rolls used depends largely on the material being treated. Slurry with a larger amount of abrasive material is better treated in the hard upper roll, e.g., steel slurry with large solid material is preferable treated with a pneumatic upper roll. The apparatus described in detail with pairs of solid deformable squeeze rolls, e.g., of rubber.

We have experimented with various layouts of apertures in the shell. In general, we have found efficient operation requires the apertures to be distributed over substantially the entire surface of the shell apart from weld regions and the upturned flanges 10 at the rims of the shell.

It is convenient to drive the lower roll 2 from the motor 8 and to gear the upper roll 2 to the lower. However, the rolls may be independently driven. In a modification the two upper rolls of FIGS. 9 are geared to each other by a sprocket and chain arrangement (see FIG. 9A). If e.g., stones force the top roll of the upper pair at least partly out of gear the additional gearing helps to maintain drive.

The apparatus is highly flexible in concept. Different roll arrangements different rolls 2 and different mesh sizes of apertures on the shell, allow all kinds of slurries, e.g., fine sludges and very coarse fibrous slurries, to be treated.

We claim:

1. A filtration apparatus comprising a filter plate constituted by a cylindrical shell rotatable around its longitudinal axis; portions of said shell defining apertures therein to allow passage of filtered liquor therethrough; a pair of squeeze rolls mounted opposite one another above and beneath the surface of said shell and in contact therewith; means for rotating said squeeze rolls, said shell being drivable by rotation of said squeeze rolls; the outer surface of said squeeze roll beneath the surface of said shell being deformable by contact with said shell; means for driving both rolls; feed means arranged to supply effluent to the top surface of said shell immediately before the nip between said shell and said squeeze rolls, in the direction of rotation of said shell by said rolls, whereby said effluent is carried by said shell into said nip and forced between said rolls under compression, filter liquor passing through said apertures in said shell and solid material being carried past said nip; means for collecting filter liquor passing through said shell; and a scraper member supported at a location beyond said nip in the direction of movement of said shell and adapted to detach solid material from the top surface of said shell.

2. A filtration apparatus according to claim 1 comprising first and second stage filters each constructed as defined in claim 1, said first stage filter being arranged in relation to said second stage filter to feed partially dewatered solid material detached from said shell in said first stage filter to said nip in said second stage filter.

3. An apparatus according to claim 1 and further comprising a further pair of opposed squeeze rolls arranged in contact with said top and bottom surfaces of said shell adjacent to said squeeze rolls and adapted to also assist in drying said shell.

4. A filtration apparatus comprising a filter plate constituted by a cylindrical shell rotatable around its longitudinal axis; portions of said shell defining apertures therein to allow passage of filtered liquor therethrough; at least one pair of squeeze rolls mounted opposite one another above and beneath the surface of said shell and in contact therewith; means for rotating said squeeze rolls, said shell being drivable by rotation of said squeeze rolls; outer surfaces for said squeeze rolls deformable by contact with said shell; means for driving both rolls; feed means arranged to supply effluent to the top surface of said shell immediately before the nip between said shell and said squeeze rolls, in the direction of rotation of said shell by said rolls, whereby said effluent is carried by said shell into said nip and forced between said rolls under compression, filter liquor passing through said apertures in said shell and solid material being carried past said nip; means for collecting filter liquor passing through said shell; a scraper member supported at a location beyond said nip in the direction of movement of said shell and adapted to detach solid material from the top surface of said shell; a further pair of opposed squeeze rolls arranged in contact with said top and bottom surfaces of said shell adjacent to said squeeze rolls and adapted'to also assist in drying said shell, and further feed means adapted to supply effluent to a region on said top surface of said shell between said nip between said pair of squeeze rolls and said shell and the further nip between said further pair of squeeze rolls and said shell.

5. An apparatus according to claim 4 wherein said further feed means adapted to supply effluent to said nip between said squeeze rolls and said shell is modified to supply fibrous material instead of effluent, whereby said fibrous material leaving said nip and entering said region on said top surface of said shell forms a receiving mat thereon to assist in filtration of mainly liquid effluent supplied by said further feed means.

6. A filtration apparatus according to claim 1 wherein said deformable surface on said squeeze rolls is composed of a deformable elastomeric material such as natural and synthetic rubbers and like material.

7. An apparatus according to claim 6, wherein said deformable surface is composed of synthetic rubber with a hardness of 85 on the British Standards scale.

8. A filtration apparatus according to claim 1 wherein said scraper member comprises a blade resiliently supported at the ends thereof and biased by its resilient support into scraping contact with said top surface of said shell.

9. An apparatus according to claim 8, wherein the region of contact between said scraper member and said shell is immediately above the center position of said shell.

10. An apparatus according to claim 1 wherein said shell is apertured over substantially the entire surface thereof.

lll. A filtration apparatus comprising a cylindrical shell rotatable around its longitudinal axis; portions 'of said shell defining a multitude of apertures extending over the entire surface of said shell to allow the passage of filtered liquor through said shell; at least one pair of squeeze rolls mounted opposite one another above and beneath said surface of said shell and in contact therewith, said shell being drivable by rotation of said squeeze rolls; at least an outer layer of said squeeze rolls deformable by contact with said shell; means for driving said rolls to cause rotation of said shell; feed means adapted to supply effluent to said surface of said shell immediately before the nip between said shell and said squeeze rolls, in the direction of rotation of said shell by said rolls, whereby effluent is carried by said shell into said nip and forced between said rolls under compression, filter liquor passing through said apertures in said shell and solid material being carried past said nip; and means for collecting filter liquor passing through said shell.

12. A filtration apparatus comprising a cylindrical shell rotatable around its longitudinal axis; portions of said shell defining a multitude of apertures extending over substantially the entire surface of said shell to allow the passage of filtered liquor through said shell; at least one pair of squeeze rolls mounted opposite one another above and beneath said surface of said shell and in contact therewith, said shell being drivable by rotation of said squeeze rolls; at least an outer layer of the lower of said squeeze rolls deformable by contact with said shell; means for driving said rolls to cause rotation of said shell; feed means adapted to supply effluent to said surface of said shell immediately before the nip between said shell and said squeeze rolls, in the direction of rotation of said shell by said rolls, whereby effluent is carried by said shell into said nip and forced between said rolls under compression, filter liquor passing through said apertures in said shell and solid material being carried past said nip; and means for collecting filter liquor passing through said shell. 

1. A filtration apparatus comprising a filter plate constituted by a cylindrical shell rotatable around its longitudinal axis; portions of said shell defining apertures therein to allow passage of filtered liquor therethrough; a pair of squeeze rolls mounted opposite one another above and beneath the surface of said shell and in contact therewith; means for rotating said squeeze rolls, said shell being drivable by rotation of said squeeze rolls; the outer surface of said squeeze roll beneath the surface of said shell being deformable by contact with said shell; means for driving both rolls; feed means arranged to supply effluent to the top surface of said shell immediately before the nip between said shell and said squeeze rolls, in the direction of rotation of said shell by said rolls, whereby said effluent is carried by said shell into said nip and forced between said rolls under compression, filter liquor passing through said apertures in said shell and solid material being carried past said nip; means for collecting filter liquor passing through said shell; and a scraper member supported at a location beyond said nip in the direction of movement of said shell and adapted to detach solid material from the top surface of said shell.
 2. A filtration apparatus according to claim 1 comprising first and second stage filters each constructed as defined in claim 1, said first stage filter being arranged in relation to said second stage filter to feed partially dewatered solid material detached from said shell in said first stage filter to said nip in said second stage filter.
 3. An apparatus according to claim 1 and further comprising a further pair of opposed squeeze rolls arranged in contact with said top and bottom surfaces of said shell adjacent to said squeeze rolls and adapted to also assist in drying said shell.
 4. A filtration apparatus comprising a filter plate constituted by a cylindrical shell rotatable around its longitudinal axis; portions of said shell defining apertures therein to allow passage of filtered liquor therethrough; at least one pair of squeeze rolls mounted opposite one another above and beneath the surface of said shell and in contact therewith; means for rotating said squeeze rolls, said shell being drivable by rotation of said squeeze rolls; outer surfaces for said squeeze rolls deformable by contact with said shell; means for driving both rolls; feed means arranged to supply effluent to the top surface of said shell immediately before the nip between said shell and said squeeze rolls, in the direction of rotation of said shell by said rolls, whereby said effluent is carried by said shell into said nip and forced between said rolls under compression, filter liquor passing through said apertures in said shell and solid material being carried past said nip; means for collecting filter liquor passing through said shell; a scraper member supported at a location beyond said nip in the direction of movement of said shell and adapted to detach solid material from the top surface of said shell; a further pair of opposed squeeze rolls arranged in contact with said top and bottom surfaces of said shell adjacent to said squeeze rolls and adapted to also assist in drying said shell, and further feed means adapted to supply effluent to a region on said top surface of said shell between said nip between said pair of squeeze rolls and said shell and the further nip between said further pair of squeeze rolls and said shell.
 5. An apparatus according to claim 4 wherein said further feed means adapted to supply effluent to said nip between said squeeze rolls and said shell is modified to supply fibrous material instead of effluent, whereby said fibrous material leaving said nip and entering said region on said top surface of said shell forms a receiving mat thereon to assist in filtration of mainly liquid effluent supplied by said further feed means.
 6. A filtration apparatus according to claim 1 wherein said deformable surface on said squeeze rolls is composed of a deformable elastomeric material such as natural and synthetic rubbers and like material.
 7. An apparatus according to claim 6, wherein said deformable surface is composed of synthetic rubber with a hardness of 70-85 on the British Standards scale.
 8. A filtration apparatus according to claim 1 wherein said scraper member comprises a blade resiliently supported at the ends theReof and biased by its resilient support into scraping contact with said top surface of said shell.
 9. An apparatus according to claim 8, wherein the region of contact between said scraper member and said shell is immediately above the center position of said shell.
 10. An apparatus according to claim 1 wherein said shell is apertured over substantially the entire surface thereof.
 11. A filtration apparatus comprising a cylindrical shell rotatable around its longitudinal axis; portions of said shell defining a multitude of apertures extending over the entire surface of said shell to allow the passage of filtered liquor through said shell; at least one pair of squeeze rolls mounted opposite one another above and beneath said surface of said shell and in contact therewith, said shell being drivable by rotation of said squeeze rolls; at least an outer layer of said squeeze rolls deformable by contact with said shell; means for driving said rolls to cause rotation of said shell; feed means adapted to supply effluent to said surface of said shell immediately before the nip between said shell and said squeeze rolls, in the direction of rotation of said shell by said rolls, whereby effluent is carried by said shell into said nip and forced between said rolls under compression, filter liquor passing through said apertures in said shell and solid material being carried past said nip; and means for collecting filter liquor passing through said shell.
 12. A filtration apparatus comprising a cylindrical shell rotatable around its longitudinal axis; portions of said shell defining a multitude of apertures extending over substantially the entire surface of said shell to allow the passage of filtered liquor through said shell; at least one pair of squeeze rolls mounted opposite one another above and beneath said surface of said shell and in contact therewith, said shell being drivable by rotation of said squeeze rolls; at least an outer layer of the lower of said squeeze rolls deformable by contact with said shell; means for driving said rolls to cause rotation of said shell; feed means adapted to supply effluent to said surface of said shell immediately before the nip between said shell and said squeeze rolls, in the direction of rotation of said shell by said rolls, whereby effluent is carried by said shell into said nip and forced between said rolls under compression, filter liquor passing through said apertures in said shell and solid material being carried past said nip; and means for collecting filter liquor passing through said shell. 